Search

The present study evaluates the potential of green coconut fiber in the production of cellulosic butanol by ABE (acetone-butanol-ethanol) fermentation, using Clostridium beijerinckii ATCC 10132. Batch fermentation tests were carried out to investigate the influence of some nutrients (sources of nitrogen and mineral medium) in the supplementation of the enzymatic hydrolyzate of pretreated green coconut husks, as well as the effects of the initial concentration of sugars and the initial concentration of inoculum on the production of butanol among other fermentation products. The mode of conducting the process in a fed-batch was carried out to improve the yield and productivity of butanol. Using the enzymatic hydrolyzate obtained with 9 g/L of sugars (glucose + xylose), the ABE fermentation reached a yield of 0.53 g/g after 96 h, in which 3.4 g/L of butanol was obtained. The absence or insufficiency of some nutrients (minerals and phosphate buffer) resulted in low yields of ABE products, indicating the importance of adapting supplements to the chosen fermentation medium and the type of microorganism used. Fed-batch increased productivity in ABE fermentation (0.08 g/L.h for butanol). The results indicate that green coconut residues have energy potential and are low-cost raw materials for the biotechnological production of butanol, as an alternative and renewable product. [ABSTRACT FROM AUTHOR]

The unwashed alkali-treated lignocellulose can be directly enzymatically hydrolyzed and fermented via pH adjustment with acids. The use of acids would give a burden on production cost. Furfural residue (FR) which is the acidic solid waste from lignocellulose-derived furfural production process was employed in this study as a pH regulator. The corn cob-derived FR was used to adjust the pH value of alkali-treated corn stover (PCS) to 4.8 for enzymatic hydrolysis and ethanol fermentation. The unwashed PCS adjusted by FR got higher enzymatic hydrolysis efficiency (EHE) than the washed PCS samples. Meanwhile, the mixing of PCS and FR had a synergistic effect on the EHE of PCS. The fermentation of enzymatic hydrolysate from unwashed PCS-FR mixture at 20% solid concentration could attain ethanol production of 26.54 ± 0.02 mg/mL with a yield of 89.53 ± 0.08%. This work created a novel recycling way of FR as a pH regulator for improving the bioconversion of alkali-treated lignocellulose. It also provided a novel clue for the valuable valorization of wastes from corn production. [ABSTRACT FROM AUTHOR]

Biomass pretreatment for the production of second-generation (2G) ethanol and biochemical products is a challenging process. The present study investigated the synergistic efficiency of purified carboxymethyl cellulase (CMCase), β-glucosidase, and xylanase from Aspergillus fumigatus JCM 10253 in the hydrolysis of alkaline-pretreated sugarcane bagasse (SCB). The saccharification of pretreated SCB was optimised using a combination of CMCase and β-glucosidase (C + β; 1:1) and addition of xylanase (C + β + xyl; 1:1:1). Independent and dependent variables influencing enzymatic hydrolysis were investigated using response surface methodology (RSM). Hydrolysis using purified CMCase and β-glucosidase achieved yields of 18.72 mg/mL glucose and 6.98 mg/mL xylose. Incorporation of xylanase in saccharification increased the titres of glucose (22.83 mg/mL) and xylose (9.54 mg/mL). Furthermore, characterisation of SCB biomass by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy respectively confirmed efficient structural disintegration and revealed the degree of crystallinity and spectral characteristics. Therefore, depolymerisation of lignin to produce high-value chemicals is essential for sustainable and competitive biorefinery development. [ABSTRACT FROM AUTHOR]

AbstractThe aim of this work is to investigate the influence of an alkaline pretreatment of the Mediterranean plant Carpobrotus edulis on the adsorption capacity toward the dye methylene blue and to estimate the content of soluble organic matter that can be released into the aqueous solution by this biomaterial. The biomaterial used was characterized by SEM-EDX, SS, FT-IR, pHZ, COD and BOD5. Removal of methylene blue (MB) dye by this biomaterial was carried out and the effects of physicochemical factors such as initial pollutant concentration, adsorbent dose, contact time, pH and temperature were investigated. After adsorbent treatment, the soluble organic matter was reduced by 97%, 96%, and 96% for biological oxygen demand, chemical oxygen demand, and organic matter, respectively. Kinetics and equilibrium studies of MB adsorption on the bioadsorbents were fitted with a pseudo-second order kinetic model and a Langmuir model, respectively. The maximum adsorption amount of the modified C. edulis plant was 153.9 mg/g at 298°K. The thermodynamic parameters show that the adsorption process was possible and spontaneous in nature. The adsorption mechanism of MB on the surface of biomaterials was attributed to the electrostatic interaction and H-bonding. The prepared biomaterial (0.016 U$ per gram) was easily regenerated with aqueous HNO3 solution, with a slight decrease in adsorption capacity up to five cycles. The results of Taguchi experimental design and analysis of variance showed that contact time, adsorbent mass and initial concentration are the most important factors affecting the removal efficiency with a contribution of 43.91%, 32.68%, and 22.95%, respectively. The maximum removal capacity of MB dye in optimal operating conditions was 99.39%, which was obtained at the optimum conditions of m = 1 g, pH 4, T = 35 °C, Ci = 1000 mg/L, tc = 5 min. These results confirm previous results obtained with the batch system and show that this absorbent is also promising for the removal of cationic dyes from wastewater. [ABSTRACT FROM AUTHOR]

In this paper, the effects of an ultrasonic power and the intensity of mechanical agitation for pulp on alkaline pretreatment of gold-bearing arsenopyrite were investigated. The effect of pulp temperature on leaching efficiency in alkaline pretreatment of arsenopyrite was investigated under ultrasound and non-ultrasound conditions. Pre-treatment was followed by gold leaching tests with a cyanide solution. Compared with the nonultrasound condition at the temperature of 60 ○C, arsenic extraction and gold extraction was increased 20 %, 14.4 %, respectively, in the presence of ultrasound at ambient temperature. The characteristics of the ultrasonic power level as a function of the intensity of mechanical agitation were evaluated by a numerical simulation with CFD software – Ansys Fluent. The simulation results demonstrated that the stronger intensity of mechanical agitation, the lower ultrasonic power level. These results were proved through leaching experiments at different rotation speeds of impeller and ultrasonic powers. The study results demonstrate that the ultrasound is an effective factor for pretreatment of gold bearing arsenopyrite and gold extraction is related to an ultrasonic power and the intensity of mechanical agitation. [ABSTRACT FROM AUTHOR]

The present work studied the effects of alkali pretreatment on the cellulosic biomass of rice straw. The improvement in the cellulose content and reduction in the lignin and hemicellulose percentage was observed with alkali pretreatment. Fourier transformation infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) analysis confirm the modification in the surface structure of alkali rice straw. Further, the study investigated the potential of different types of seed sludge as inoculum sources for dark fermentative biohydrogen production. In comparison to other sludge samples (beverage industry, food industry, and sewage treatment plant sludge), the mixed culture of sewage treatment plant sludge had the highest cumulative volume of biohydrogen (90.52 mL), as well as the highest hydrogen production yield (0.75 moleH2/mole) with the substrate utilization of 86.72%. The results provide information on the best sludge source for enhancing biohydrogen production in the dark fermentation method. [ABSTRACT FROM AUTHOR]

Banana (Musa acuminata) cultivation and trade are widespread across various regions and countries globally. Nonetheless, substantial quantities of waste, primarily comprising leaves and stems of the banana plant, are annually disposed of into the environment post-harvest. This study aims to highlight this issue and propose an alternative solution in response to the escalating demand for raw materials. To this end, alkaline pretreatment was administered to particles derived from banana waste leaves and stems using NaOH solutions at concentrations of 1%, 3%, and 5%, followed by board production. Results indicate that water absorption (WA) and thickness swelling (TS) values of the produced boards increased with alkaline treatment. However, the mechanical properties stipulated in the TS-EN 312 (2012) standard were satisfactorily achieved with 1% NaOH treatment, while higher concentrations adversely affected internal bond strength (IB), modulus of elasticity (MOE), and modulus of rupture (MOR). In the surface properties tests of the boards, increasing the alkali concentration decreased values of the surface roughness and the contact angle. Overall, the findings suggest the viability of utilizing banana waste as an alternative resource.

Spent mushroom compost is one of the main potentials for biogas production. In recent years, several studies employed adding nanoparticles and alkaline pretreatment for improving biogas production. The present study is one of the pioneer studies that employ hybrid alkaline pretreatment (0, 5, and 15 mg of NaOH) and zero-valent iron nanoparticles (0, 10, 20, 30, and 40 mg) for improving the co-digestion of spent mushroom compost and rice straw. According to the results, retention time (RT) and nanoparticle (NP) concentrations have the most significant impact on biomethane production (significant at 1% probability level), while the NaOH concentration has the lowest impact on biomethane production (significant at 5% probability level) in comparison with RT and NP concentration. Also, the maximum biomethane production is related to NP40Na15 (about 200% higher than the control). The minimum cumulative biomethane production is related to NP0Na15 (about 30% lower than the control). The lowest relative environmental midpoint impact is related to NP40Na15, which was on average about 60% lower than the control. Adding NPs at high concentrations of NaOH reduces the midpoint impacts. The results of the study could lead to new, ecologically friendly biomethane production methods that make better use of agricultural and organic wastes.

Alkaline pretreatment stands out as a valuable strategy in biomass conversion to overcome the recalcitrance of biomass by removing lignin and a part of hemicellulose. This enhances enzyme accessibility and promotes saccharification. However, increasing the alkaline concentration to enhance the delignification and improve glucose yield together presents inherent limitations. In this experiment the amount of delignification and glucose yield resulting from surfactant associated with sonication during mild alkaline pretreatment of Eucalyptus pellita was investigated. Also, the effect of various factors (sonication temperature and surfactant immersion time) on delignification and glucose yield were examined. The results demonstrated that surfactant associated with sonication pretreatment could overcome the limitation of alkaline pretreatment and could increase the amount of delignification alongside enzymatic hydrolysis glucose yield of Eucalyptus pellita wood by around 90%. The findings indicated that surfactant-assisted with sonication during mild alkaline pretreatment of Eucalyptus pellita (i.e., hardwood) could be recommended as a supporting pretreatment method for the production of monomeric sugars. [ABSTRACT FROM AUTHOR]

This review paper examines acid and alkaline pretreatments on perennial grasses for second-generation (2G) bioethanol production, a relatively unexplored area in this field. It compares the efficiency of these pretreatments in producing fermentable sugar and bioethanol yield. This study finds that alkaline pretreatment is more effective than acidic pretreatment in removing lignin and increasing sugar yield, leading to higher ethanol yields. However, it is costlier and requires longer reaction times than acidic pretreatment, while acidic pretreatment often leads to the formation of inhibitory compounds at higher temperatures, which is undesirable. The economic and environmental impacts of lignocellulosic biomass (LCB) are also assessed. It is revealed that LCB has a lower carbon but higher water footprint and significant costs due to pretreatment compared to first-generation biofuels. This review further explores artificial intelligence (AI) and advanced technologies in optimizing bioethanol production and identified the gap in literature regarding their application to pretreatment of perennial grasses. This review concludes that although perennial grasses hold promise for 2G bioethanol, the high costs and environmental challenges associated with LCB necessitate further research. This research should focus on integrating AI to optimize the pretreatment of LCB, thereby improving efficiency and sustainability in 2G biofuel production. [ABSTRACT FROM AUTHOR]

In order to improve the biogas production from sweet sorghum bagasse (SSB) pretreated with alkaline hydrogen peroxide and reveal the influence of zeolite dosage and TE on the anaerobic digestion performance, as well as the synergistic effect of zeolite dosage and TE, three dosages of zeolite and trace elements (TE) were used as additives for batched biogas production from pretreated sweet sorghum bagasse slurry (PSSBS). The results showed that the maximum methane production of 274.5 mL/g volatile solid (VS) from the group of PSSBS + 5 g/L zeolite + 1 mL TE could be obtained and 58.4% higher than that of untreated sweet sorghum bagasse. Modified Gompertz model estimation demonstrated that the PSSBS + 5 g/L zeolite + 1 mL TE group caused the highest methane production rate to improve by up to 41.6% from SSB and by at least 39.9% from PSSBS. Moreover, with the zeolite and TE addition, activities of cellulase and dehydrogenase of the digestate analysis indicated a positive influence on biogas production and the high alkalinity maintained the stability of the system. This work will provide experimental reference for biogas production from sweet sorghum bagasse. [ABSTRACT FROM AUTHOR]

Alkaline pretreatment stands out as a valuable strategy in biomass conversion to overcome the recalcitrance of biomass by removing lignin and a part of hemicellulose. This enhances enzyme accessibility and promotes saccharification. However, increasing the alkaline concentration to enhance the delignification and improve glucose yield together presents inherent limitations. In this experiment the amount of delignification and glucose yield resulting from surfactant associated with sonication during mild alkaline pretreatment of Eucalyptus pellita was investigated. Also, the effect of various factors (sonication temperature and surfactant immersion time) on delignification and glucose yield were examined. The results demonstrated that surfactant associated with sonication pretreatment could overcome the limitation of alkaline pretreatment and could increase the amount of delignification alongside enzymatic hydrolysis glucose yield of Eucalyptus pellita wood by around 90%. The findings indicated that surfactant-assisted with sonication during mild alkaline pretreatment of Eucalyptus pellita (i.e., hardwood) could be recommended as a supporting pretreatment method for the production of monomeric sugars.

The Vietnamese food industry produces a lot of coffee pulp, which is a valuable and abundant source of agricultural by-products. It contains a lot of cellulose, which can be converted into bioethanol. However, coffee pulp needs an extensive pretreatment to reduce the amount of lignin and hemicellulose while retaining the initial cellulose composition. This study compared several pre-hydrolysis and pre-fermentation pretreatment methods which involved H2 SO4 , NaOH, microwaves, and white rot fungus Phanerochaete chrysosporium. The hemicellulose dropped by 43.8% after the acidic pretreatment, by 47.1% after the alkaline pretreatment, and by 12.8% after the microbial pretreatment. The lignin contents dropped by 4.2, 76.6, and 50.2% after acidic, alkaline, and microbial pretreatment, respectively. The removal of hemicellulose and lignin in the coffee pulp was much more efficient when two or three of the pretreatment methods were combined. The microwave-assisted acid and alkaline pretreatment was the most efficient method: it removed 71.3% of hemicellulose and 79.2% of lignin. The combined method also had the highest amount of reducing sugars and glucose in hydrolysate. Additionally, concentrations of such yeast inhibitors as 5-hydroxymethyl-2-furaldehyde (HMF) and furfural were 2.11 and 3.37 g/L, respectively. The acid pretreatment was effective only in removing hemicellulose while the alkaline pretreatment was effective in lignin removal; the fungal pretreatment had low results for both hemicellulose and lignin removals. Therefore, the combined pretreatment method was found optimal for coffee pulp.

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This review paper examines acid and alkaline pretreatments on perennial grasses for second-generation (2G) bioethanol production, a relatively unexplored area in this field. It compares the efficiency of these pretreatments in producing fermentable sugar and bioethanol yield. This study finds that alkaline pretreatment is more effective than acidic pretreatment in removing lignin and increasing sugar yield, leading to higher ethanol yields. However, it is costlier and requires longer reaction times than acidic pretreatment, while acidic pretreatment often leads to the formation of inhibitory compounds at higher temperatures, which is undesirable. The economic and environmental impacts of lignocellulosic biomass (LCB) are also assessed. It is revealed that LCB has a lower carbon but higher water footprint and significant costs due to pretreatment compared to first-generation biofuels. This review further explores artificial intelligence (AI) and advanced technologies in optimizing bioethanol production and identified the gap in literature regarding their application to pretreatment of perennial grasses. This review concludes that although perennial grasses hold promise for 2G bioethanol, the high costs and environmental challenges associated with LCB necessitate further research. This research should focus on integrating AI to optimize the pretreatment of LCB, thereby improving efficiency and sustainability in 2G biofuel production.

Alkaline pretreatment can improve the methane yields and dewatering performance of anaerobically digested sludge, but it still needs to be coupled with other conditioning methods in the practical dewatering process. This study utilized four different flocculants and a skeleton builder for conditioning of alkaline pretreatment-anaerobically digested sludge. Chitosan was found to be the most effective in dewatering the sludge. Chitosan coupled with rice husk powder further improved the dewatering performance, which reduced normalized capillary suction time, specific resistance to filtration, and moisture content by 98.7%, 82.0%, and 12.1%. For land use of biogas slurry as a fertilizer, chitosan conditioning promoted the growth of corn seedlings, while the other three flocculants diminished the growth of corn seedlings. Chitosan coupled with rice husk powder further promoted the growth of corn seedlings by 103.5%, 65.0%, and 53.7% in fresh weight, dry weight, and root length, respectively. Overall, chitosan coupled with rice husk powder not only enhanced the dewaterability of alkaline pretreatment-anaerobically digested sludge but also realized the resource utilization of agricultural waste. [Display omitted] • Alkaline pretreatment increased methane yield by 35.2%. • Alkaline pretreatment enhanced the dewaterability of anaerobically digested sludge. • The conditioning effect of chitosan was better than that of other flocculants. • The addition of rice husk powder can further improve the conditioning effect. • Both chitosan and rice husk powder promoted the growth of corn seedlings. [ABSTRACT FROM AUTHOR]

Lignocellulosic biorefinery faces challenges associated with high energy input during pretreatment and high enzyme cost for enzymatic hydrolysis of cellulose, as well as the intricate valorization of lignin and hemicellulose. This study applied KOH-urea pretreatment to obtain maximum lignin removal of 68.93 % from rice straw at 80 °C for 60 min. The pretreatment consumed only 10.49 % of the total energy input. Five-time dilution of neutral black liquor can optimally stimulate the plant growth. Enzymatic conversion of KOH-urea-treated rice straw attained 92.02 % at 20 % solid concentration with 10 FPU cellulase/g substrate. The ethanol concentration achieved 37.02 g/L at a yield of 75.89 %. The solid residue after fermentation contained 42.40 % dietary fiber and 16.70 % protein, which is suitable as animal feed. This study developed a simple bio-circular way to concurrently produce liquid fertilizer, bioethanol, and animal feed from rice straw. [Display omitted] • KOH-urea pretreatment shared only 10.49 % of total energy consumption. • Enzymatic conversion of rice straw reached 92.02 % at 20 % solid concentration. • Black liquor can be prepared as fertilizer after pH adjustment and proper dilution. • Solid residues after fermentation are suitable as animal feed. • A feasible bio-circular way of lignocellulosic biorefinery is constructed. [ABSTRACT FROM AUTHOR]

[Display omitted] Corn stover has been identified as a key resource in the transition from petrochemicals to sustainably sourced energy and materials; however, the as-recovered lignin from alkaline pretreatment contains unusually high levels of residual impurities, which must be removed to maximize potential application. Thus, the Aqueous Lignin Purification using Hot Agents (ALPHA) process was applied to a corn stover lignin containing ∼10 % carbohydrates and ∼3 % ash. Lignin fractions ∼100 times cleaner than the feed lignin and of controlled molecular weight (i.e., as low as one-fifth and as high as triple the absolute molecular weight (Mw) of the feed) were obtained. The ALPHA solvent was a hot (60 or 75 °C) solution of 80 % ethanol combined with the feed lignin at an unusually low, 3:1 solvent-to-feed lignin ratio – conditions that create the liquid–liquid equilibrium (LLE) phase split needed to practice ALPHA. Lignin fractionation then commenced by adding water to the original solution, decreasing the ethanol content in increments of 3–4 wt%. Surprisingly, the highest Mw fractions did not precipitate until the solution contained just below 50 % ethanol, by which point almost half of the starting lignin of near-average Mw had already precipitated. Another unexpected result was that the lignin waste stream from the initial purification step could be increased from 40 to 98 % lignin in a single equilibrium stage simply by re-processing that waste with another 80 % ethanol solution at the conditions given above. In summary, the efficacy of ALPHA for purifying and fractionating an impurities-laden corn stover lignin to ultraclean levels in a scalable manner requiring only aqueous bioethanol solutions has been demonstrated. [ABSTRACT FROM AUTHOR]

Lignin hydrolyzes during alkali-heat pretreatment of lignocellulose, due to the cleavage of covalent linkages between lignin and lignin-carbohydrate complex. Various structure of lignin monomers are responsible of the complicated hydrolysis mechanism of lignin and lignin-carbohydrate complex. This study used density functional theory to reveal the hydrolysis mechanism of lignin with various substituents and lignin-carbohydrates complex with different linkages. The results indicated that the S N 2 reaction was observed to take place in the lignin. Methoxy groups and methyl group had an insignificant influence on hydrolysis reaction pathway of lignin, whereas the presence of a methyl group on the α-carbon atom had a hindering effect on the nucleophilic attack during alkaline pretreatment. The lignin-carbohydrate complex with different linkage showed a significant difference in hydrolysis reaction pathway. Additionally, the reaction energy barrier of ester bond hydrolysis was lowest among the hydrolysis of ester bond, phenyl glycosidic bond, benzyl ether bond, γ-ester bond, coumarin ester bond and acetal bond under alkaline condition. This study provides valuable insights into the process control, reactor design, and performance enhancement for lignocellulose pretreatment. • Mechanism of lignin hydrolysis in alkali thermal pretreatment was studied by DFT. • Mechanism of LCC hydrolysis in alkali thermal pretreatment was studied by DFT. • S N 2 reaction was observed to take place during the lignin hydrolysis. • A methyl group on the α-carbon atom hindered the nucleophilic attack. • Reaction energy barrier of ester bond hydrolysis was lowest during LCC hydrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The NTR of the ISFPD system was 77.3% under initial pH 9. • The PD rates were comparable when subjected to high nitrate concentrations. • High nitrate and pH promoted the release of organics in sludge fermentation. • Macromolecules needed to be hydrolyzed to be available for PD. Achieving partial denitrification (PD) by using fermentation products extracted from waste activated sludge (WAS) rather than commercial organic matters is a promising approach for providing nitrite for anammox, while sludge reduction could also be realized by WAS reutilization. This study proposed an In-situ Sludge Fermentation coupled with Partial Denitrification (ISFPD) system and explored its performance under different conditions, including initial pH, nitrate concentrations, and organic matters. Results showed that nitrite production increased with the elevation of initial pH (from 6 to 9), and the highest nitrate-to-nitrite transformation ratio (NTR) reached 77% at initial pH 9. The PD rates and NTR were observed to be minimally influenced by initial nitrate concentrations. Acetate was preferred by denitrifying bacteria, while macromolecules such as proteins necessitated be hydrolyzed to be suitable for further utilization. The insights gained through this study paved the way for efficient nitrite production and sustainable WAS reutilization in harmony. [ABSTRACT FROM AUTHOR]

Beyond the conventional consideration of pretreatment severity (PS) responsible for biomass disruption, the influence of reagent properties on biomass (LCB) disruption is often overlooked. To investigate the LCB disruption as a function of reagent properties, reagents with distinct cations (NaOH and KOH) and significantly higher delignification potential were chosen. NaOH solution (3 % w/v) with a measured pH of 13.05 ± 0.01 is considered the reference, against which a KOH solution (pH = 13.05 ± 0.01) was prepared for LCB pretreatment under the same PS. Despite comparable lignin content, varying glucose yield of NaOH (68.76 %) and KOH (46.88 %) pretreated residues indicated the presence of heterogeneously disrupted substrate. Holocellulose extracted from raw poplar (ASC, control) and alkaline pretreated residues (C-NaOH and C-KOH) were analyzed using HPLC, XRD, SEM, TGA/DTG, XPS, and 13CP MAS NMR to investigate the pretreatment-induced structural modification. Results revealed that, despite the same pretreatment severity, better disruption in C-NaOH (higher accessible fibril surface and less-ordered region) leading to higher digestibility than C-KOH, likely due to the smaller ionic radius of Na+, facilitates better penetration into dense LCB matrix. This study elucidates the importance of considering the reagent properties during LCB pretreatment, eventually enhancing consciousness while selecting reagents for efficient LCB utilization. [Display omitted] • Emphasized considering the inherent properties of reagents for biomass pretreatment • Different reagents disrupted biomass heterogeneously under the same pretreatment severity (PS) • Under the same PS, NaOH transformed substrate in favor of enzymatic hydrolysis than KOH • The small ionic radius of Na+ facilitated penetration into the biomass matrix • Extracted holocellulose from NaOH-pretreated residue exhibited more amorphous region than KOH [ABSTRACT FROM AUTHOR]

• Increasing textile waste generation has risen European Union to implement regulations and strategies. • Chemo-enzymatic treatment of blended textiles enabled selective hydrolysis and removal of cellulose allowing polyester recovery. • Precise condition adjustment is crucial to avoid polyester damage and ensure complete cellulose removal. • Optimized conditions can transform the textile industry from linear to circular, reducing the amount of textile waste. • Industrial implementation realises a sustainable textile biorefinery concept. The study demonstrates the potential of enzymatic hydrolysis and alkaline pretreatment for sustainable blended textile recycling. The target is complete cellulose removal while preserving the polyester integrity for recovery. Interactions of sodium hydroxide concentration (10 %–30 %), urea concentration (0 %–12 %), and temperature (-20 °C–50 °C) were investigated during pretreatment using a design of experiments. Analysis revealed a bimodal pattern in polyester mass loss, with one peak at lower concentrations and temperatures, and a more prominent peak at higher concentrations and temperatures. Cellulose hydrolysis also occurred under high NaOH concentrations and elevated temperatures (50 °C, 30 % NaOH, 0 % urea). Optimal conditions, preserving polyester integrity while achieving complete cellulose elimination, were identified at temperatures between 6.2 °C and 13.3 °C, with NaOH concentrations of 20.7 %–26.6 % (0 % urea) or 13.9 % NaOH and 12 % urea. These findings pave the way for a greener, more efficient textile recycling, advancing the circularity for textiles. [Display omitted] [ABSTRACT FROM AUTHOR]

Bamboo is a promising biomass resource. However, the complex multilayered structure and chemical composition of bamboo cell walls create a unique anti-depolymerization barrier, which increases the difficulty of separation and utilization of bamboo. In this study, the relationship between the connections of lignin-carbohydrate complexes (LCCs) within bamboo cell walls and their multilayered structural compositions was investigated. The chemical composition, structural properties, dissolution processes, and migration mechanisms of LCCs were analyzed. Alkali-stabilized LCC bonds were found to be predominantly characterized by phenyl glycoside (PhGlc) bonds along with numerous p -coumaric acid (PCA) linkage structures. As demonstrated by the NMR and CLSM results, the dissolution of the LCC during the alkaline pretreatment process was observed to migrate from the inner secondary wall (S-layer) of the bamboo fiber cell walls to the cell corner middle lamella (CCML) and compound middle lamella (CML), ultimately leading to its release from the bamboo. Furthermore, the presence of H-type lignin-FA-arabinoxylan linkage structures within the bamboo LCC was identified with their primary dissolution observed in the S-layer of the bamboo fiber cell walls. The study results provided a clear target for breaking down the anti-depolymerization barrier in bamboo, signifying a major advancement in achieving the comprehensive separation of bamboo components.